Substituted urea and isothiourea derivatives as no synthase inhibitors

ABSTRACT

The use of an N-substituted urea derivative for the manufacture of a medicament for the treatment of a condition where there is an advantage in inhibiting the NO synthase enzyme, in particular cerebral ischemia, and pharmaceutical formulations therefor are disclosed. Novel N-substituted urea derivatives and processes for the preparation thereof are also described.

This application is a 371 of PCT/GB94/02138 filed Oct. 3, 1994, whichclaims priority to U.S. application Ser. No. 08/131,794 filed Oct. 4,1993, now abandoned.

The present invention relates to N-substituted urea derivatives, tomethods for their manufacture, to pharmaceutical compositions containingthem and to their use in therapy, in particular their use as inhibitorsof nitric oxide synthase, and in particular neuronal nitric oxidesynthase.

It has been known since the early 1980's that the vascular relaxationbrought about by acetylcholine is dependent on the presence of theendothelium and this activity was ascribed to a labile humoral factortermed endothelium-derived relaxing factor (EDRF). The activity ofnitric oxide (NO) as a vasodilator has been known for well over 100years and NO is the active component of amyl nitrite, glyceryltrinitriteand other nitrovasodilators. The recent identification of EDRF as NO hascoincided with the discovery of a biochemical pathway by which NO issynthesised from the amino acid L-arginine by the enzyme NO synthase.

NO is the endogenous stimulator of the soluble guanylate cyclase and isinvolved in a number of biological actions in addition toendothelium-dependent relaxation including cytotoxicity of phagocyticcells and cell-to-cell communication in the central nervous system (seeMoncada et al, Biochemical Pharmacology, 38, 1709-1715 (1989) andMoncada et al, Pharmacological reviews, 43, 109-142 (1991)). It is nowthought that excess NO production may be involved in a number ofconditions, particularly conditions which involve systemic hypotensionsuch as toxic shock and therapy with certain cytokines.

The synthesis of NO from L-arginine can be inhibited by the L-arginineanalogue N^(G) -monomethyl-L-arginine (L-NMMA) and the therapeutic useof L-NMMA for the treatment of toxic shock and other types of systemichypotension has been proposed (WO 91/04024 and GB-A-2240041). Thetherapeutic use of certain other NO synthase inhibitors apart fromL-NMMA for the same purpose has also been proposed in WO 91/04024 and inEP-A-0446699. Other potent NO synthase inhibitors are described inNarayanan et al., J. Med. Chem. 37, 885-887 (1994).

It has recently become apparent that there are at least three types ofNO synthase enzymes as follows:

(i) a constitutive, Ca⁺⁺ /calmodulin dependent enzyme, located in theendothelium, that releases NO in response to receptor or physicalstimulation.

(ii) a constitutive, Ca⁺⁺ /calmodulin dependent enzyme, located in thebrain, that releases NO in response to receptor or physical stimulation.

(iii) a Ca⁺⁺ independent enzyme which is induced after activation ofvascular smooth muscle, macrophages, endothelial cells, and a number ofother cells by endotoxin and cytokines. Once expressed this inducible NOsynthase synthesises NO for long periods.

The NO released by the constitutive enzyme acts as a transductionmechanism underlying several physiological responses. The function ofthe NO produced by the inducible enzyme is as a cytotoxic molecule fortumour cells and invading microorganisms. It also appears that theadverse effects of excess NO production, in particular pathologicalvasodilation and tissue damage, may result largely from the effects ofNO synthesised by the inducible NO synthase.

It is believed that NO synthesis plays an important part in thepathology of a range of diseases of the nervous system, eg. ischemia.However, non-selective inhibitors of NO synthases cause profound changesin blood pressure and blood flow, including cerebral blood flow.Unfortunately, ischemic injury inherently reduces the blood supply tothe brain and any further decrease in blood flow caused by anon-selective NO synthase inhibitor would have a deleterious effect,potentially opposing any beneficial effect of decreased NO productionwithin the brain. Nevertheless, studies of middle cerebral arteryocclusion in both rats and mice have demonstrated a substantialprotection effect of low doses of NO synthase inhibitors (see forexample Nowicki et al, Eur. J Pharmacol., 1991, 204, 339-340). At highdoses, or in models of global ischemia, these inhibitors fail to provideprotection. Thus, there is a need for a potent inhibitor of neuronal NOsynthase with preferably little or no activity against the vascularendothelial NO synthase.

The NO synthase inhibitors proposed for therapeutic use so far, such asL-NMMA and L-NAME (L-nitroarginine methyl ester), are non-selective inthat they inhibit all NO synthase enzymes identified to date. Use ofsuch a non-selective NO synthase inhibitor would require great care tobe taken in order to avoid the potentially serious consequences ofover-inhibition of the other enzymes. Thus, whilst non-selective NOsynthase inhibitors have therapeutic utility provided that appropriateprecautions are taken, NO synthase inhibitors which are selective in thesense that they inhibit one NO synthase enzyme to a considerably greaterextent compared to one or more of the other enzymes would be of evengreater therapeutic benefit and much easier to use.

Unpublished PCT patent application PCT/GB93/02437 discloses a class ofS-substituted isothiourea derivatives which inhibit the NO synthaseenzymes, showing a slight selectivity of the inducible enzyme over theconstitutive enzymes.

It has been found that a class of N-substituted urea derivatives orsalts, esters or amides thereof are NO synthase inhibitors, showingselectivity of the neuronal NO synthase enzyme over the endothelial andinducible NO synthase enzymes. The term "urea derivatives" when usedherein means "isothiourea derivatives" and "isourea derivatives".

In one aspect the present invention provides the use of an N-substitutedurea derivative or a salt, ester or amide thereof, other thanN-(2,6-dimethylphenyl)-5,6-dihydro4H-1,3-thiazin-2-amine, for themanufacture of a medicament for the treatment of a condition where thereis an advantage in inhibiting the neuronal NO synthase enzyme with lessinhibition of the endothelial or inducible NO synthase enzymes.

In another aspect, the present invention provides a method of treatmentof a condition where there is an advantage in inhibiting the neuronal NOsynthase enzyme with less inhibition of the endothelial or inducible NOsynthase enzyme comprising administering to a mammal in need thereof atherapeutically effective amount of an N-substituted urea derivative ora salt, ester or amide thereof, other thanN-(2,6-dimethylphenyl)-5,6-dihydro4H-1,3-thiazin-2-amine.

More specifically, the present invention provides the use of aN-substituted urea derivative or salt, ester or amide thereof other thanN-(2,6-dimethylphenyl)-5,6-dihydro-4H-1,3-thiazin-2-amine for themanufacture of a medicament for the treatment of a disease of thenervous system due to over production of the neuronal nitric oxidesynthase enzyme. Such diseases include cerebral ischemia, CNS trauma,epilepsy, AIDS dementia, chronic neurodegenerative disease and chronicpain, and conditions in which non-adrenergic non-cholinergic nerve maybe implicated such as priapism, obesity and hyperphagia, particularlycerebral ischemia.

In one embodiment of the present invention the N-substituted ureaderivative is an N-substituted isothiourea derivative, other thanN-(2,6-dimethylphenyl)-5,6-dihydro4H-1,3-thiazin-2-amine, preferably anN,S-disubstituted isothiourea derivative. In a second embodiment of thepresent invention the N-substituted urea derivative is an N-substitutedisourea, preferably an N,O-disubstituted isourea derivative.

Preferred urea derivatives include those of the formula (I) ##STR1##wherein

Q is oxygen or sulphur

R¹ is hydrogen or C₁₋₈ hydrocarbyl;

R² is a mono- or bicyclic heterocyclic ring system, a C₁₋₁₀ hydrocarbylgroup which may optionally contain an oxygen atom, a group S(O)_(n)wherein n is 0, 1 or 2, or a group NR³ wherein R³ is hydrogen or a C₁₋₆aliphatic group, each group R² optionally being substituted by one tofive groups independently selected from

(i) C₁₋₆ alkyl or C₃₋₆ cycloalkyl each optionally substituted by one tothree halo atoms;

(ii) a group OR⁴ wherein R⁴ is hydrogen, C₁₋₆ alkyl, phenyl or benzyl;

(iii) a halo atom;

(iv) a group CO₂ R⁵ wherein R⁵ is hydrogen or C₁₋₄ alkyl;

(v) a group NR⁶ R⁷ wherein R⁶ and R⁷ are independently selected fromhydrogen, C₁₋₄ alkyl or a group ##STR2## wherein Q and R¹ are ashereinbefore defined; (vi) nitro; or

(vii) cyano;

or R¹ may be linked to the imino nitrogen to form a monocyclicheterocyclic ring; with the exception ofN-(2,6-dimethylphenyl)-5,6-dihydro4H-1,3-thiazin-2-amine.

A preferred group of compounds are those of formula (I) with the provisothat when Q is sulphur and R¹ is hydrogen or C₁₋₅ alkyl, R² is not anornithine or lysine derivative optionally substituted by a C₁₋₆ alkylgroup on either the α-, β- or γ-carbon atoms, or a tautomer thereof.

One embodiment of the present invention provides compounds of formula(I) as hereinbefore defined with the proviso that R¹ is not linked tothe imino nitrogen to form a monocyclic heterocyclic ring.

In one preferred embodiment, Q is oxygen.

In a second preferred embodiment, Q is sulphur.

When Q is either oxygen or sulphur:

suitably R¹ is hydrogen, C₁₋₄ alkyl, C₂₋₅ alkenyl or benzyl; preferablyR¹ is C₁₋₄ alkyl for example ethyl;

suitably, R² is a 5- or 6- membered heterocyclic ring or a 9- or10-membered bicyclic heterocyclic ring, a phenyl ring, or a C₂₋₈ alkylchain which optionally contains a group S(O)_(n) as hereinbeforedefined, or a C₂₋₄ alkyl chain which contains a phenylene ring, eachgroup R² optionally being substituted by one to five groupsindependently selected from

(i) a C₁₋₄ alkyl group optionally substituted by one to three fluoroatoms:

(ii) a cyclohexyl ring;

(iii) a group OR^(4a) wherein R^(4a) is hydrogen, methyl, ethyl, phenylor benzyl;

(iv) fluoro, chloro or bromo;

(v) a group CO₂ R^(5a) wherein R^(5a) is hydrogen, methyl or ethyl;

(vi) a group NR^(6a) R^(7a) wherein R^(6a) and R^(7a) are independentlyselected from hydrogen, methyl or ethyl or one of R^(6a) and R^(7a) is agroup ##STR3## as hereinbefore defined and the other is hydrogen; (vii)nitro; or

(viii) cyano;

or R¹ may be linked to the imino nitrogen in the compound of formula (I)to form a thiazole or thiazoline ring.

Formula (I) includes compounds of formulae (IA) to (IF) ##STR4## whereinZ is oxygen or sulphur; R¹ is as hereinbefore defined; X is a C₂₋₉hydrocarbyl group which may optionally contain an oxygen atom, a groupS(O)_(n) as hereinbefore defined, or a group NR³ as hereinbeforedefined; T is a C₁₋₈ hydrocarbyl group optionally containing a 5- or6-membered heterocyclic ring, or T is a C₂₋₄ hydrocarbyl groupcontaining a phenylene ring; and Ar is a mono- or bicyclic aromatic ringsystem optionally substituted by one to five groups selected from

(i) C₁₋₆ alkyl or C₃₋₆ cycloalllyl each optionally substituted by one tothree halo atoms;

(ii) a group OR⁴ wherein R⁴ is hydrogen, C₁₋₆ alkyl, phenyl or benzyl;

(iii) a halo atom;

(iv) a group CO₂ R⁵ wherein R⁵ is hydrogen or C₁₋₄ alkyl;

(v) a group NR⁶ R⁷ wherein R⁶ and R⁷ are independently selected fromhydrogen, C₁₋₄ alkyl or a group ##STR5## wherein Q and R¹ are ashereinbefore defined; (vi) nitro; or

(vii) cyano;

In the formulae (IA) to (IF);

Suitably, R¹ is a C₁₋₆ hydrocarbyl group, preferably a C₁₋₄ alkyl group,e.g. ethyl.

Suitably, X is a C₂₋₆ hydrocarbyl group and preferably a C₃₋₅ alkyleneor alkenylene group.

Suitably, T is C₁₋₈ hydrocarbyl containing a 5- or 6-memberedheterocyclic ring; or a C₂₋₄ hydrocarbyl group containing a phenylenering.

Suitably Ar is phenyl optionally substituted by one to threesubstituents which may be the same or different and are selected fromC₁₋₄ alkyl or C₃₋₆ cycloalkyl groups each optionally substituted by oneto three halo atoms; C₁₋₄ alkoxy groups; hydroxy groups, benzyloxygroups; halo atoms; CO₂ R⁵ groups wherein R⁵ is hydrogen or C₁₋₄ alkyl;groups NR⁶ R⁷ wherein R⁶ and R⁷ are independently selected from hydrogenor C₁₋₄ alkyl. Most suitably Ar is phenyl substituted by one or twosubstituents, preferably one substituent.

Preferably Ar is phenyl substituted by C₁₋₃ alkoxy, hydroxy, benzyloxy,halo atoms or C₁₋₄ alkyl optionally substituted by one to three fluoroatoms, C₁₋₃ alkoxy, hydroxy, benzyloxy, or halo atoms.

One preferred embodiment of the present invention includes compounds offormula (IA) wherein X is a C₂₋₉ hydrocarbyl group which contains anoxygen atom, a group S(O)_(n) or NR³ wherein n and R³ are ashereinbefore defined, and compounds of formulae (IB) to (IF) ashereinbefore defined.

Suitable compounds of the formula (I) include:

S-Ethyl-N-(4-phenoxyphenyl)isothiourea

S-ethyl-N-(3-methoxyphenyl)isothiourea

S-ethyl-N-[4-(benzyloxy)phenyl]isothiourea

S-ethyl-N-[4-(ethoxycarbonyl)phenyl]isothiourea

S-ethyl-N-(4-carboxyphenyl)isothiourea

S-ethyl-N-(3-carboxyphenyl)isothiourea

S-ethyl-N-(2-bromophenyl)isothiourea

S-ethyl-N-(4-dimethylaminophenyl)isothiourea

S-ethyl-N-(4-cyclohexylphenyl)isothiourea

S-ethyl-N-(4-hydroxyphenyl)isothiourea

S-ethyl-N-(4-methoxyphenyl)isothiourea

S-ethyl-N-(2-pyridyl)isothiourea

S-Ethyl-N-[4-trifluoromethyl)phenyl]isothiourea

S-Benzyl-N-[4-(trifluoromethyl)phenyl]isothiourea

S-Ethyl-N-(3-chlorophenyl)isothiourea

S-Ethyl-N-(2-isopropylphenyl)isothiourea

S-Ethyl-N-(4-isopropylphenyl)isothiourea

S-Ethyl-N- [3 -(trifluoromethyl)phenyl]isothiourea

S-Ethyl-N-[2-(trifluoromethyl)phenyl]isothiourea

S-Ethyl-N-[2-(chlorophenyl)isothiourea

S-Ethyl-N-(2-methoxyphenyl)isothiourea

S-Ethyl-N-(4-methylphenyl)isothiourea

S-Ethyl-N-(3 -pyridyl)isothiourea

S-Ethyl-N-(4-chloro-3-(trifluoromethyl)phenyl) isothiourea

S-Ethyl-N-(2-chloro-5-(trifluoromethyl)phenyl) isothiourea

S-Ethyl-N-(3-pyridyl)isothiourea

S-Ethyl-N-(4-pyridyl)isothiourea

O-Methyl-N-(4-(trifluoromethyl)phenyl)isourea

O-Ethyl-N-(4-(trifluoromethyl)phenyl)isourea

S-Ethyl-N-[4-(trifluoromethoxy)phenyl]isothiourea

N5-(2-thiazolin-2-yl)-L-ornithine

N6-(2-thiazolin-2-yl)-L-lysine

N,N'-((methylthio)iminomethyl)-m-xylylenediamine

N,N-((methylthio)iminomethyl)-p-xylylenediamine

N5-(imino(methylthio)methyl-L-ornithine

N5-((ethylthio)iminomethyl)-L-ornithine

N6-(imino(methylthio)methyl)-L-lysine

N6-((ethylthio)iminomethyl)-L-lysine

N5-(imino(1 -methylethylthio)methyl)-L-ornithine

N6-(imino(1-methylethylthio)methyl)-L-lysine

N5-(imino(2-methylpropylthio)methyl)-L-ornithine

N6-(imino(2-methylpropylthio)methyl)-L-lysine

N5-((methylthio)iminomethyl)-D-ornithine

N6-((methylthio)iminomethyl)-D-lysine

N5-((ethylthio)iminomethyl)-D-ornithine

N6-((ethylthio)iminomethyl)-D-lysine

N5-(imino(1-methylethylthio)methyl)-D-ornithine

N6-((1-methylethylthio)iminomethyl)-D-lysine

N5-((2-methylpropylthio)iminomethyl)-D-ornithine

N6-((methylpropylthio)iminomethyl)-D-Iysine

N5-(iminomethoxymethyl)-L-ornithine

N5-(ethoxyiminomethyl)-L-ornithine

N5-(iminoisopropoxymethyl)-L-ornithine

N6-iminomethoxymethyl)-L-lysine

N6-(ethoxyiminomethyl)-L-lysine

1-(3-(Aminomethyl)benzyl)-O-ethylisourea

1-(3-(Aminomethyl)benzyl)-S-methylisothiourea

1-(3-(Aminomethyl)benzyl)-S-ethylisothiourea

1-(4-(Aminomethyl)benzyl)-S-methylisothiourea

1-(4-(Aminomethyl)benzyl)-S-ethylisothiourea

S-ethyl-N-(4-diethylamino)phenyl) isothiourea

S-ethyl-N-(5-chloro-2-pyridyl)isothiourea

S-ethyl-N-(4-nitrophenyl) isothiourea

S-ethyl-N-(4-chlorophenyl) isothiourea

S-ethyl-N-(3, 4-dichlorophenyl) isothiourea

S-benzyl-N-phenyl isothiourea

S-ethyl-N-phenyl isothiourea

and salts, esters or amides thereof.

By the term "hydrocarbyl" group is meant a group that contains onlycarbon and hydrogen atoms and may contain double and/or triple bonds andwhich may be cyclic or aromatic in nature. An oxygen atom, or a groupS(O)_(n) or NR³ as hereinbefore defined, may optionally intersperse thecarbon atoms in the hydrocarbyl chain.

By the term "aliphatic" is meant an alkyl, alkenyl, alkynyl orcycloalkyl group. The terms alkyl, alkenyl and allynyl are intended toinclude both straight and branched chain variants.

By the term "heterocyclic ring" is meant a cyclic compound containingone to three heteroatoms selected from oxygen, sulphur and nitrogen, andpreferably nitrogen and sulphur.

The compounds of formula (I) may include a number of asymmetric centresin the molecule depending on the precise meaning of the various groupsand the present invention is intended to include all possible isomers.

When R¹ is hydrogen, compounds of formula (I) may exist in tautomericform and the present invention includes all such forms.

Certain compounds of formula (I) have also been found to have activityagainst the inducible NO synthase enzyme and may be of use in thetreatment of systemic hypotension associated with septic and/or toxicshock induced by a wide variety of agents, therapy with cytokines suchas TNF, IL-1 and IL-2 and therapy with cytokine-inducing agents such as5,6-dimethylxanthenone acetic acid, as an adjuvant to short termimmunosuppression in transplant therapy, and in the treatment ofautoimmune and/or inflammatory conditions affecting the joints, forexample arthritis. Accordingly, the present invention further providesthe use of a compound of formula (I) other than5-methyl-2-(2-thiazolylamino)phenol and S-ethyl-N-phenylisothiourea forthe manufacture of a medicament for the treatment of a conditionrequiring inhibition of the inducible NO synthase enzyme.

In a further aspect the present invention provides a N-substituted ureaderivative of formula (I) other than S-ethyl-N-phenylisothiourea,S-ethyl-N-(2-chlorophenyl) isothiourea,S-ethyl-N-(2-trifluoromethylphenyl)isothiourea, 2-propenylthiourea,N-(2,6-dimethylphenyl)-5,6-dihydro4H-1,3-thiazin-2-amine and5-methyl-2-(2-thiazolyl amino)phenol, or a pharmaceutically acceptablesalt, ester or amide thereof for use in medicine.

The present invention also provides a N-substituted urea derivative offormula (I) or a salt, ester or amide thereof, with the proviso that:

(a) when Q is sulphur and

(i) R¹ is methyl, R² is not a phenyl ring substituted by 3-chloro,2-ethyl, 2-chloro-5-trifluoromethyl, 3-trifluoromethyl, 3-methyl.3-bromo, 4-nitro, 4-chloro, 3,4-dichloro or CO₂ H; or R² is not a group5-chloro-2-pyridyl;

(ii) R¹ is ethyl, R² is not a phenyl ring or a phenyl ring substitutedby 4-methoxy, 2-chloro, 4-hydroxy, 2-methoxy 4-methyl, 2-trifluoromethylor 3-trifluoromethyl; or

(b) the compound of formula (I) is not 2-propenylthioureaN-(2,6-dimethylphenyl)-5,6-dihydro4H- 1,3-thiazin-2-amine5-methyl-2-(2-thiazolylamino)phenol.

The present invention includes N-substituted urea derivatives in theform of salts, esters or amides, in particular acid addition salts.Suitable salts include those formed with both organic and inorganicacids. Such acid addition salts will normally be pharmaceuticallyacceptable although salts of non-pharmaceutically acceptable salts maybe of utility in the preparation and purification of the compound inquestion. Thus, preferred salts include those formed from hydrochloric,hydrobromic, sulphuric, citric, tartaric, phosphoric, lactic, pyruvic,acetic, trifluoroacetic, succinic, oxalic, fumaric, maleic, oxaloacetic,methanesulphonic, ethanesulphonic, p-toluenesulphonic, benzenesulphonicand isethionic acids. Salts of N-substituted urea derivatives can bemade by reacting the appropriate compound in the form of the free basewith the appropriate acid. Esters are pharmaceutically acceptableesters, for example C₁₋₄ alkyl esters.

As used herein, reference to "treatment" of a patient is intended toinclude prophylaxis.

The activity of compounds of formula (a) as inhibitors of isolated NOsynthase enzymes has been demonstrated against NO synthase enzymesisolated from the human placenta, the human brain and carcinoma cells.

Whilst it may be possible for the compounds of formula (I) to beadministered as the raw chemical, it is preferable to present them as apharmaceutical formulation. According to a further aspect, the presentinvention provides a pharmaceutical formulation comprising a compound offormula (I) or a pharmaceutically acceptable salt, ester or amidethereof, other than S-ethyl-N-phenylisothiourea,S-ethyl-N-(2-chlorophenyl)isothiourea, S-ethyl-N-(2-trifluoromethylphenyl)isothiourea, 2-propenyl thiourea,N-(2,6-dimethylphenyl)-5,6-dihydro4H-1,3-thiazin-2-amine and5-methyl-2-(2-thiazolylamino)phenol, together with one or morepharmaceutically acceptable carriers therefor and optionally one or moreother therapeutic ingredients. The carrier(s) must be "acceptable" inthe sense of being compatible with the other ingredients of theformulation and not deleterious to the recipient thereof.

The formulations include those suitable for oral, parenteral (includingsubcutaneous, intradermal, intravenous and intraarticular), rectal andtopical (including dermal, buccal, sublingual and intraocular)administration although the most suitable route may depend upon forexample the condition and disorder of the recipient. The formulationsmay conveniently be presented in unit dosage form and may be prepared byany of the methods well known in the art of pharmacy. All methodsinclude the step of bringing into association a compound of formula (I)or a pharmaceutically acceptable salt, ester or amide thereof ("activeingredient") with the carrier which constitutes one or more accessoryingredients. In general the formulations are prepared by uniformly andintimately bringing into association the active ingredient with liquidcarriers or finely divided solid carriers or both and then, ifnecessary, shaping the product into the desired formulation.

Formulations of the present invention suitable for oral administrationmay be presented as discrete units such as capsules, cachets or tabletseach containing a predetermined amount of the active ingredient; as apowder or granules; as a solution or a suspension in an aqueous liquidor a non-aqueous liquid; or as an oil-in-water liquid emulsion or awater-in-oil liquid emulsion. The active ingredient may also bepresented as a bolus, electuary or paste.

A tablet may be made by compression or moulding, optionally with one ormore accessory ingredients. Compressed tablets may be prepared bycompressing in a suitable machine the active ingredient in afree-flowing form such as a powder or granules, optionally mixed with abinder, lubricant, inert diluent, lubricating, surface active ordispersing agent. Moulded tablets may be made by moulding in a suitablemachine a mixture of the powdered compound moistened with an inertliquid diluent. The tablets may optionally be coated or scored and maybe formulated so as to provide slow or controlled release of the activeingredient therein.

Formulations for parenteral administration include aqueous andnon-aqueous sterile injection solutions which may contain anti-oxidants,buffers, bacteriostats and solutes which render the formulation isotonicwith the blood of the intended recipient; and aqueous and non-aqueoussterile suspensions which may include suspending agents and thickeningagents. The formulations may be presented in unit-dose or multi-dosecontainers, for example sealed ampoules and vials, and may be stored ina freeze-dried (lyophilised) condition requiring only the addition ofthe sterile liquid carrier, for example, saline, or water-for-injection,immediately prior to use. Extemporaneous injection solutions andsuspensions may be prepared from sterile powders, granules and tabletsof the kind previously described.

Formulations for rectal administration may be presented as a suppositorywith the usual carriers such as cocoa butter or polyethylene glycol.

Formulations for topical administration in the mouth, for examplebuccally or sublingually, include lozenges comprising the activeingredient in a flavoured basis such as sucrose and acacia ortragacanth, and pastilles comprising the active ingredient in a basissuch as gelatin and glycerin or sucrose and acacia.

Preferred unit dosage formulations are those containing an effectivedose, as hereinbelow recited, or an appropriate fraction thereof, of theactive ingredient.

It should be understood that in addition to the ingredients particularlymentioned above, the formulations of this invention may include otheragents conventional in the art having regard to the type of formulationin question, for example those suitable for oral administration mayinclude flavouring agents.

The compounds of the invention may be administered orally or viainjection at a dose of from 0.1 to 500 mg/kg per day. The dose range foradult humans is generally from 5 mg to 35 g/day, preferably 5 mg to 2g/day and most preferably 10 mg to 1 g/day. Tablets or other forms ofpresentation provided in discrete units may conveniently contain anamount of compound of the invention which is effective at such dosage oras a multiple of the same, for instance, units containing 5 mg to 500mg, usually around 10 mg to 200 mg.

The compounds of formula (I) are preferably administered orally or byinjection (intravenous or subcutaneous). The precise amount of compoundadministered to a patient will be the responsibility of the attendantphysician. However the dose employed will depend on a number of factors,including the age and sex of the patient, the precise disorder beingtreated, and its severity. Also the route of administration may varydepending on the condition and its severity.

The invention further includes a process for the preparation of thenovel compounds of formula (I), analagous to those known in the art forpreparing N-substituted ureas.

Thus:

(a) Compounds of formula (I) wherein Q is S may be prepared by thereaction of a compound of formula (II)

    H.sub.2 N--R.sup.2                                         (II)

wherein R² is as hereinbefore defined, with a compound having athiocarbonyl group, followed if necessary by hydrolysis to give acompound of formula (I) wherein R¹ is hydrogen or a tautomer thereof,and thereafter the optional conversion to a compound of formula (I)wherein R¹ is other than hydrogen by allylation of the sulphur atom ofthe isothiourea

The coupling reaction may be carried out between a compound of formula(II) and a compound having a thiocarbonyl group, for examplethiophosgene followed by ammonia as described in Tet. Lett. 1991, 32 (7)875-878 or a compound of formula (II) and an isothiocyanate, such asbenzoyl isothiocyanate. Suitably the reaction is carried out in a polarsolvent, such as dichloromethane, chloroform, ethanol or acetone at anon-extreme temperature of from -78° C. to 200° C., for example -5° C.to 10° C. and preferably room temperature. The intermediate thiourea,e.g. benzoylthiourea, may be hydrolysed in a polar solvent such as 10%sodium hydroxide solution at a non-extreme temperature of from -20° C.to 200° C., such as the refluxing solvent temperature.

The alkylation is generally carried out using a compound of formula R¹-L, wherein R¹ is as hereinbefore defined other than hydrogen and L is asuitable leaving group. Suitable leaving groups include a halo atom, forexample iodo.

Compounds of formula (II) are commercially available or may be preparedby methods known in the art.

(b) Compounds of formula (I) wherein Q is O may be prepared by the acidcatalysed addition of

(i) an alcohol of formula R¹ -OH to prepare a compound wherein R¹ is ashereinbefore defined other than hydrogen; or

(ii) water to prepare a compound wherein R¹ is hydrogen

to a compound of formula (III) ##STR6##

or a protected derivative thereof, wherein R² is as hereinbeforedefined, followed by deprotection where necessary.

The acid catalysed addition is suitably carried out using the alcohol(R¹ -OH or water) as the solvent, at a non-extreme temperature of 0° C.to 100° C., and preferably room temperature, in the presence of an acid,e.g. hydrochloric acid, conveniently in solution in ether.

Compounds of formula (III) may be prepared by the reaction of a compoundof formula (II) as hereinbefore defined with a compound of formula L'-CNwherein L' is a leaving group, for example a halo atom such as bromo.The reaction may be carried out in ether as a solvent at a non-extremetemperature of from -20° C. to 100° C., suitably 0° C.

The present invention will now be illustrated by way of example only.

Proton (¹ H) NMR analysis was consistent with the proposed structure inall cases.

EXAMPLE 1 Preparation of S-Ethyl-N-(4-phenoxyphenyl)isothiourea

To a stirred solution of 1-(4-phenoxyphenyl)-2-thiourea (2.00 g, 8.19mmol) in acetone (20 ml) was added iodoethane (7.61 g, 48.7 mmol). Themixture was heated to reflux for three hours, cooled to room temperatureand concentrated at reduced pressure. The resulting viscous oil wascrystallized from acetone-pentane to affordS-ethyl-N-(4-phenoxyphenyl)isothiourea hydroiodide as a beige solid.Mp=140-143° C.

The following compounds were made by an analagous method:

    ______________________________________                                        Ex. No.                                                                             Compound                  MP ° C.                                ______________________________________                                        1A    S-ethyl-N-(3-methoxyphenyl)isothiourea                                                                   75-77.sup.a                                  1B    S-ethyl-N-[4-(benzyloxy)phenyl]isothiourea                                                              172-174.sup.b                                 1C    S-ethyl-N-[4-(ethoxycarbonyl)phenyl]isothiourea                                                          80-85.sup.a                                  1D    S-ethyl-N-(4-carboxyphenyl)isothiourea                                                                  214-215.sup.a                                 1E    S-ethyl-N-(3-carboxyphenyl)isothiourea                                                                  149-215.sup.c                                 1F    S-ethyl-N-(2-bromophenyl)isothiourea                                                                     89-100.sup.d                                 1G    S-ethyl-N-(4-dimethylaminophenyl)isothiourea                                                            138-141.sup.e                                 1H    S-ethyl-N-(4-cyclohexylphenyl)isothiourea                                                               174-175.sup.a                                 1I    S-ethyl-N-(4-hydroxyphenyl)isothiourea                                                                  135.sup.e                                     1J    S-ethyl-N-(4-methoxyphenyl)isothiourea                                                                  127-128.sup.f                                 1K    S-ethyl-N-(2-pyridyl)isothiourea                                                                        161-163.sup.g                                 ______________________________________                                         .sup.a = Recrystallized from acetonepentane                                   .sup.b = Triturate with pentane                                               .sup.c = Triturated with pentane, followed by hot ethyl acetate               .sup.d = Triturated with hot ethyl acetate                                    .sup.e = Recrystallized from acetonepentane, and then from ethanolethyl       acetate                                                                       .sup.f = Recrystallized from ethyl acetatehexane                              .sup.g = Recrystallized from methanolether                               

EXAMPLE 2 Preparation of S-Ethyl-N-[4-trifluoromethyl)phenyl]isothiourea

To a stirred suspension of 1-[4-trifluoromethyl)phenyl]-2-thiourea (3.00g, 13.6 mmol) in acetone (50 mL) was added iodoethane (6.63 g, 42.5mmol). The mixture was heated to reflux and stirred overnight. Aftercooling to room temperature, the mixture was concentrated at reducedpressure. The resulting red viscous oil was poured into saturated NaHCO₃and extracted with ether. The organic layer was dried over magnesiumsulphate and filtered. The filtrate was acidified with 1N hydrochloricacid in ether, diluted with pentane and stirred for 20 minutes. Theyellow solid was collected and recrystallized from ethanol-ether toafford S-ethyl-N-[4-(trifluoromethyl)phenyl]isothiourea hydrochloride(2.71 g, 70%) as a white solid. Mp=127° C. Anal. Calcd for C₁₀ H₁₁ N₂SF₃.HCl: C, 42.18; H,4.25; N, 9.84; S, 11.26; Cl, 12.45. Found: C,42.22; H, 4.20; N, 9.85; S, 11.20; Cl, 12.43.

The following compounds were made by an analagous method:

    ______________________________________                                        Ex. No                                                                              Compound                  MP ° C.                                ______________________________________                                        2A    S-Benzyl-N-[4-(trifluoromethyl)phenyl]isothiourea                                                        71-72.sup.a                                  2B    S-Ethyl-N-(3-chlorophenyl)isothiourea                                                                    95-96.sup.b                                  2C    S-Ethyl-N-(2-isopropyiphenyl)isothiourea                                                                 66-68.sup.a                                  2D    S-Ethyl-N-(4-isopropylphenyl)isothiourea                                                                113-116.sup.a                                 2E    S-Ethyl-N-[3-(trifluoromethyl)phenyl]isothiourea                                                        102.sup.a                                     2F    S-Ethyl-N-[2-(trifluoromethyl)phenyl]isothiourea                                                         75-77.sup.a                                  2G    S-Ethyl-N-[2-(chlorophenyl)isothiourea                                                                   87-90.sup.a                                  2H    S-Ethyl-N-(2-methoxyphenyl)isothiourea                                                                   75-78.sup.b                                  2I    S-Ethyl-N-(4-methylphenyl)isothiourea                                                                   138-141.sup.a                                 2J    S-Ethyl-N-(3-pyridyl)isothiourea                                                                        180-182.sup.c                                 2K    S-Ethyl-N-(4-chloro-3-(trifluoromethyl)phenyl)                                                          143.sup.a                                           isothiourea                                                             2L    S-Ethyl-N-(2-chloro-5-(trifluoromethyl)phenyl)                                                          155-156.sup.d                                       isothiourea                                                             2M    S-Ethyl-N-(4-pyridyl)isothiourea                                                                        151-152.sup.e                                 ______________________________________                                         .sup.a = Triturated with pentane                                              .sup.b = Recrystallised from acetonepentane                                   .sup.c = Recrystallised from ethanolether                                     .sup.d = Recrystallisation not required                                       .sup.e = Free base purified by silica gel chromatography                 

EXAMPLE 3 Preparation of O-Methyl-N-(4-(trifluoromethyl)phenyl)isourea

To a stirred, cooled (0° C.) solution of 4-aminobenzotrifluoride (1.61g, 10.0 mmol) in methanol (10 ml) was added a solution of cyanogenbromide (1,17 g, 11.0 mmol) in methanol (10 ml) dropwise. The mixturewas allowed to warm to room temperature and stirred for 5 days. Thesolvent was removed at reduced pressure and the residue was partitionedbetween diethyl ether and water. The organic layer was dried over sodiumsulphate and filtered. Solvent was removed at reduced pressure. Theresidue was chromatographed on silica gel eluting with 20% ethyl acetatein hexane to give 660 mg of a solid (mp=117-126° C.).

To a stirred, cooled (0° C.) solution of the above solid (172 mg, 0.93mmol) in methanol (10 ml) was added 1N hydrochloric acid in diethylether (0.93 ml, 0.93 mmol). After 20 minutes the mixture was warmed toroom temperature, stirred for 10 hours, and concentrated at reducedpressure. The residue was triturated with diethyl ether and filtered toafford 149 mg (63%) of O-Methyl-N-(4-(triluoromethyl)phenyl)isourea as alight beige solid. Mp=121-123° C.

The following compound was prepared by an analagous method:

    ______________________________________                                        3A   O-Ethyl-N-(4-(trifluoromethyl)phenyl)isourea                                                           117-119° C.                              ______________________________________                                    

EXAMPLE 4 Preparation ofS-Ethyl-N-[4-(trifluoromethoxy)phenyl]isothiourea

To a stirred solution of 4-(trifluoromethoxy)aniline (5.24 g, 2.6 mmol)in acetone (100 ml) was added benzoyl isothiocyanate (5.46 g, 33.5mmol). After stirring overnight at room temperature, the mixture wasconcentrated at reduced pressure giving a yellow solid.Recrystallization from ethyl acetate-hexane afforded 9.29 g (92%) of apale yellow solid. Mp=124-125° C.

To a stirred solution of the above solid (7.80 g, 22.9 mmol) intetrahydrofuran (100 ml) was added 2.0N aqueous sodium hydroxide (25 ml,50.0 mmol). The mixture was heated to reflux for 3 h, cooled to roomtemperature and then concentrated at reduced pressure. The residue wassuspended in water and extracted repeatedly with dichloromethane. Thecombined organic layers were washed with brine and dried over magnesiumsulphate. Solvent was removed at reduced pressure giving a solid.Recrystallization from ethyl acetate-hexane afforded 3.77 g (70%) of awhite solid. Mp=136-137° C.

To a stirred solution of the above white solid (3.00 g, 12.7 mmol) inacetone (100 ml) was added iodoethane (5.85 g, 37.5 mmol). The mixturewas heated to reflux and stirred overnight. After cooling to ambienttemperature, the mixture was concentrated at reduced pressure giving anoil. The oil was dissolved in water and washed with pentane. The aqueouslayer was poured into saturated aqueous sodium hydrogen carbonate (75ml) and extracted with ether. The organic layer was dried over magnesiumsulphate, concentrated at reduced pressure to a volume of 200 mL andtreated with 1N hydrochloric acid (15 ml, 15.0 mmol) in ether. Thismixture was stirred for 20 minutes, concentrated at reduced pressure andplaced in vacuo overnight to give a gummy foam. Trituration of the foamwith pentane gave a solid which was collected and dried in vacuo toafford S-ethyl-N-[4-(trifluoromethoxy) phenyl]isothiourea hydrochloride(3.35 g, 88%) as a white solid. Mp=96-97° C.

EXAMPLE 5 Preparation of N⁵ -(2-thiazoin-2-yl)-L-ornithine

To a solution ofN5-carbonylbenzyloxy-N2-tert-butyloxycarbonyl-L-ornithine tert-butylester (2.2 g, 5.2 mmol) (Feldman, Tet. Lett. 1991, 32 (7), 875-878) inethyl acetate (50 ml) was added 10% palladium on carbon (1.0 g). Thesuspension was shaken at 22° C. under 50 psi H₂ for 30 minutes in a 500ml Parr bottle. The catalyst was removed by filtration through celite.The resulting solution was concentrated to yield the amine intermediate(1.5 g) as a crude oil. To a solution of the amine intermediate intetrahydrofuran (20 ml) and triethylamine (1 ml) was addedchloroethylisothiocyanate (650 mg, 5.35 mmol) as a solution intetrahydrofaran (10 ml) at 20° C. The mixture was stirred for 16 hours,filtered, concentrated, and purified by silica gel chromatographyeluting with ethyl acetate to yield the thiazoline intermediate (1.2 g,62%) as a white foamy solid. The thiazoline foam was taken up into amixture of trifluoroacetic acid (9.5 ml), water (0.5 ml), thioanisole(0.5 ml), phenol (0.75 g) and 1,2-ethanediol (0.25 ml) at 0° C. Thesolution was stirred for two hours at 20° C. and concentrated to avolume of 3 ml. The solution was rapidly stirred and diethyl ether (50ml) was added. After decanting and washing with ether, the residue waspurified by silica gel chromatography (ammonium hydroxide: methanol,gradient, 0:100 to 3:97) to yield N⁵ -(2-thiazolin-2-yl)-L-ornithine(480 mg, 69%) as a white solid, ¹ H NMR (300 MHz, D₂ O) δ 3.36 (t, J=7.4Hz, 2H), 3.54 (m,1H), 3.38 (t,J=7.4 Hz, 2H), 3.27 (t, J=6.7Hz, 2H),1.8-1.55 (m,4H).

The following compound was made by an analagous method:

    ______________________________________                                        5A             N.sup.6 -(2-thiazolin-2-yl)-L-lysine                           ______________________________________                                    

1H NMR (200 MHz, D₂ O) δ 3.85(t, J=7.3 Hz, 2H) 3.53 (m, 1H), 3,37 (t,J=7.4 Hz, 2H), 3.24 (t,J=6.8Hz, 2H), 1.8-1.65(m,2H), 1.65-1.5 (m, 2H),1.45-1.3 (m,2H)

EXAMPLE 6 Preparation ofN,N'-((methylthio)iminomethyl)-m-xylylenediamine

To a stirred solution of p-xylylene diamine (3.3 ml, 25 mmol) indichloromethane (100 ml) at 0° C. was added benzoylisothiocyanate (7.0ml, 52.0 mmol). The reaction mixture was stirred for 16 hours withgradual warming to room temperature. The solvent was removed underreduced pressure and the yellow-coloured solid slurried in hot ethanolto yield a pale yellow solid. This solid was suspended in 100 mL of 10%sodium hydroxide solution and heated to reflux for exactly five minutes.The solution was acidified with concentrated hydrochloric acid, thenmade basic with concentrated ammonium hydroxide. As the solution cools,an off-white, granular solid forms that is washed with hot 95% ethanoland dried to give a bis-thiourea intermediate (4.82 g). The bis-thioureaintermediate (2.54 g, 10 mmol) was stirred at 22° C. in dimethylformamide (25 ml) with iodomethane (5.0 ml, 80.0 mmol) for 72 hours. Thesolution was concentrated to a thick oil and purified by preparative C18reverse phase chromatography. Elution with 95:5:0.1 water: methanol:trifluoroacetic acid gave an oil. The oil was taken up into hot absoluteethanol and ethyl acetate. Upon cooling,N,N'-((methylthio)iminomethyl)-m-xylyenediamine (4.28 g) was isolated asa white solid (m.p.=164-167° C.).

EXAMPLE 7 Preparation of N,N-((methylthio)iminomethyl)-p-xylylenediamine

The intermediate bis-thiourea (5.92 g) was prepared fromp-xylylenediamine (3.4 G, 25 mmol) as described in Example 5. To asolution of the bis-thiourea intermediate (1.27 g, 5 mmol) indimethylformamide (25 ml) was added iodomethane (2.5 ml, 40 mmol). Thesolution was stirred at 22° C. for 72 hours, and the solvent was removedunder reduced pressure to yield a crude, amber-coloured oil. The crudeproduct was taken up into hot ethanol (40 mL) and treated with 160 mL ofethyl acetate with scratching to induce crystallization. The solutionwas cooled overnight, filtered, and dried in vacuo at 60° C. for 48hours to yield N,N-((methylthio)iminomethyl)-p-xylylenediamine (2.29 g,87%) as a light yellow solid (m.p.=209-212° C.).

EXAMPLE 8 Preparation of N⁵ -(iminomethylthio)methyl-L-ornithine

N² -Tertbutoxycarbonyl-L-thiocitrulline tert-butyl ester (Tett. Lett.(1991) 32(7), 875-878) (4 g, 12.0 mmol) was treated with 7.5 mL (120mmol) iodomethane in 30 mL anhydrous acetonitrile at 20° C. withstirring for 4 hours. The solution was concentrated to a yellow foam andstirred with a 0° C. mixture of trifluoroacetic acid (30 mL), phenol(2.25 g), water (1.0 mL), thioanisole (1.0 mL), and 1,2-ethanedithiol(0.5 mL) for 1.5 hours. The mixture was concentrated under reducedpressure to a volume of 5 mL and 80 mL ether was added with rapidstirring. The resulting grainy residue was washed with ether severaltimes and then dissolved into a minimum amount of methanol (10 mL). A50/50 solution of ammonium hydroxide and methanol was added untilinitial spotting on litmus paper indicated a pH of 8. Upon standing at20° C. for 16 hours, a white precipitate was collected by filtration anddried under reduced pressure at 100° C. to yield N⁵-(imino(methylthio)methyl-L-ornithine (2.15 g, 56%) as a white solid asthe mono-trifluoroacetic acid salt (m.p.=207-208, dec.).

EXAMPLE 9 Preparation of N⁵ -(ethylthio)iminomethyl)-L-ornithine

N² -tert-butoxycarbonyl-L-thiocitrulline tert-butyl ester (1.3 g, 3.89mmol) in 20 mL anhydrous acetonitrile was stirred with 1.21 g (7.75mmol) iodoethane at 20° C. for 60 hours. The solution was concentratedto a tan-coloured foam (1.75 g). This crude solid was treated at 0° C.with stirring for 2 hours with a solution of 14 mL trifluoroacetic acid,2.25 g phenol, 1.5 mL thioanisole, 1.5 mL water, and 0.75 mL1,2-ethanedithiol. The mixture was partially concentrated and 100 mLdiethylether was added. The resulting residue was washed with etherseveral times and purified by silica gel chromatography eluting withmethanol followed by 1% ammonium hydroxide in methanol solution. Thepooled product fractions were concentrated and passed through a reversephase C18 column eluting with methanol/water mixtures containing 0.1%heptafluorobutyric acid. After freeze-drying, the material was passedthrough a second C18 column eluting with methanol/water mixturescontaining 0.1% trifluoroacetic acid. Concentration of the pooledproduct fraction gave 336 mg of the bis-TFA salt (19% overall yield) asa hygroscopic glass. ¹ H NMR (300 MHz, D₂ O) δ 3.92 (t, J=6.1Hz,1H),3.41 (t, J=6.6Hz, 2H), 3.09 (q, J=7.3Hz, 2H), 1.95 (m, 2H), 1.75 (m,2H), 1.32 (t, J=7.3Hz, 3H).

The following compounds were prepared by an analogous method:

    ______________________________________                                        9A  N.sup.6 -(imino(methylthio)methyl)-L-lysine prepared from N.sup.2             -tert-butoxy-                                                                 carbonyl-L-homothiocitrulline tert-butyl ester                                Mass spectrum (CI) 220 (MH+, 100%)                                        9B  N.sup.6 -((ethylthio)iminomethyl)-L-lysine                                    Mass spectrum (CI) 234 (MH+, 70%)                                         9C  N.sup.5 -(imino(1-methylethylthio)methyl)-L-ornithine                         Mass spectrum (FAB) 234.2 (MH+)                                           9D  N.sup.6 -(imino(1-methylethylthio)methyl)-L-lysine                            Mass spectrum (FAB) 248.2 (MH+)                                           9E  N.sup.5 -(imino(2-methylpropylthio)methyl)-L-ornithine                        Mass spectrum (FAB) 248.2 (MH+)                                           9F  N.sup.6 -(imino(2-methylpropylthio)methyl)-L-lysine                           Mass spectrum (FAB) 262.3 (MH+)                                           9G  N.sup.5 -((methylthio)iminomethyl)-D-ornithine                                Mass spectrum (CI) 205.9 (MH+, 79%)                                       9H  N.sup.6 -((methylthio)iminomethyl)-D-lysine                                   Mass spectrum (CI) 220.0 (MH+, 97%)                                       9I  N.sup.5 -((ethylthio)iminomethyl)-D-ornithine                                 Mass spectrum (FAB) 220.2 (MH+, 100%)                                     9J  N.sup.6 -((ethylthio)iminomethyl)-D-lysine                                    Mass spectrum (FAB) 234.0 (MH+, 100%)                                     9K  N.sup.5 -(imino(1-methylethylthio)methyl)-D-ornithine                         TLC: 2% NH.sub.4 OH/MeOH on silica gel, Rf = 0.34                         9L  N.sup.6 -((1-methylethylthio)iminomethyl)-D-lysine                            TLC: 2% NH.sub.4 OH/MeOH on silica gel, Rf = 0.34                         9M  N.sup.5 ((2-methylpropylthio)iminomethyl)-D-ornithine                         Mass spectrum (FAB) 248.1 (MH+, 100%)                                     9N  N.sup.6 -((methylpropylthio)iminomethyl)-D-lysine                             TLC: 2% NH.sub.4 OH/MeOH on silica gel, Rf = 0.38                         ______________________________________                                    

EXAMPLE 10 Preparation of N⁵ (iminomethoxyethyl)-L-ornithinedihydrochloride

a. N² -(tert-butoxycarbonyl)-N⁵ -cyano-L-ornithine tert-butyl ester

To a solution of 6.1 g (14.44 mmol) N⁵ -((Benzyloxy)carbonyl)-N²-(tert-butoxycarbonyl)-L-ornithine tert-butyl ester in 100 mL ethylacetate was added 1.0 g 10% palladium on carbon. The suspension wasshaken at 22° C. under 50 psi H₂ for 45 minutes in a 500 mL Parr bottle.The catalyst was removed by filtration through celite. The resultingsolution was concentrated to yield a crude oil. The oil was dissolvedinto 50 mL of diethyl ether and added dropwise to a 0° C. stirredsolution of 1.52 g (14.3 mmol) of cyanogen bromide in 30 mL ether. Thesolution was stirred for 2 h, poured into aqueous sodium bicarbonate,and extracted with ether. The ether solution was dried (magnesiumsulfate), concentrated, and purified by silica gel chromatography (100g, 230-400 mesh silica gel). Elution with a gradient of ethyl acetate inhexanes (30%-60%) gave 3.0 g (67% yield) N² -(tert-butoxycarbonyl)-N⁵-cyano-L-ornithine tert-butyl ester as an oil.

b. N² -(tert-butoxycarbonyl)-N⁵ -(iminomethoxyethyl)-L-ornithinetert-butyl ester hydrochloride

To a solution of 1.05 g (3.35 mmol) N² -(tert-butoxycarbonyl)-N⁵-cyano-L-ornithine tert-butyl ester in 25 mL methanol at 0° C. was added3.35 mL of 1.0 M hydrochloric acid in ether solution. The solution wasstirred overnight (14 h), concentrated, and purified by silica gelchromatography. Elution with a gradient of methanol in dichloromethane(0%-15%) gave 0.95 g (74% yield) N² -(tert-butoxycarbonyl)-N⁵-(iminomethoxymethyl)-L-ornithine tert-butyl ester hydrochloride.

By the method described above for the preparation of N²-(tert-butoxycarbonyl)-N⁵ -(iminomethoxymethyl)-L-ornithine tert-butylester hydrochloride, 1.05 g (3.35 mmol) of N² -(tert-butoxycarbonyl)-N⁵-cyano-L-ornithine tert-butyl ester produced 0.95 g (75%) N²-(tert-butoxycarbonyl)-N⁵ -(ethoxyiminomethyl)-L-ornithine tert-butylester hydrochloride (TLC, silica gel, methanol:dichloromethane/1:4,Rf=0.61) and 1.195 g (3.2 mmol) of N² -(tert-butoxycarbonyl)-N⁵-cyano-L-ornithine tert-butyl ester produced 0.63 g (63%) N²-(tert-butoxycarbonyl)-N⁵ -(iminoisopropoxymethyl)-L-ornithinetert-butyl ester hydrochloride (TLC, silica gel, methanol: dichloromethane/1:4, Rf=0.53). Mass Spectrum (CI) 360 (MH⁺, 100%).

c. i) Preparation of N⁵ -(iminomethoxyethyl)-L-ornithine dihydrochloride

A solution of 0.75 g (1.96 mmol) N² -(tert-butoxycarbonyl)-N⁵-(iminomethoxymethyl)-L-ornithine tert-butyl ester hydrochloride in 2 mLdioxane at 0° C. was treated with 15 mL of 4N hydrochloric acid indioxane solution. The solution was stirred overnight at 22° C.,concentrated to a crude paste, and freeze-dried from 8 mL of water. Theproduct was freeze-dried a second time to yield 0.53 g N⁵-(iminomethoxymethyl)-L-ornithine dihydrochloride. The product analyzedsolvated with an additional 0.2 molar hydrochloric acid. 0.1 molarwater, and 0.3 molar dioxane

ii) Preparation of N⁵ -(ethoxyiminomethyl)-L-ornithine dihydrochloride.

By the method described above for the preparation of N⁵-(iminomethoxymethyl)-L-ornithine dihydrochloride, 0.78 g (1.97 mmol) N²-(tert-butoxycarbonyl)-N⁵ -(ethoxyiminomethyl)-L-ornithine tert-butylester hydrochloride was deprotected to yield 0.51 g (94%) N⁵-(ethoxyiminomethyl)-L-ornithine dihydrochloride monohydrate. TLC(silica gel, ammonium hydroxide:methanol/1:25) Rf=0.24. Mass spectrum(CI) 204 (MH⁺, 74%).

iii) Preparation of N⁵ -(iminomethyl)-L-ornithine dihydrochloride

To a 0° C. stirred solution of 0.54 g (1.32 mmol) N²-(tert-butoxycarbonyl) N⁵ -(iminoisopropoxymethyl)-L-ornithinetert-butyl ester hydrochloride in 2 ml dioxane was added 10 mL of 4Nhydrochloric acid in dioxane solution. The solution was stirred 14 hleaving a pale yellow precipitate. The dioxane was removed under reducedpressure and the residue suspended in ether. After stirring for 3 h, theether was decanted and the solids dried under vacuum to give 0.52 g N⁵-(iminoisopropoxymethyl)-L-ornithine dihydrochloride. TLC (silica gel,ammonium hydroxide:methanol/1:25) Rf=0.27.

EXAMPLE 11 Preparation of N⁶ -iminomethoxymethyl)-L-lysinedihydrochloride

a. N² -(tert-butoxycarbonyl)-N⁶ (cyano)-L-lysine tert-butyl ester

N⁶ -((benzyloxy)carbonyl)-N² -(tert-butoxycarbonyl)-L-lysine tert-butylester was hydrogenated at 20° C. under 50 psi hydrogen in 100 mL ethylacetate for 1 h. The catalyst was removed by filtration through celiteand the amine intermediate isolated without further purification as anoil (3.05 g). The amine intermediate was taken into 40 mL ether and thesolution added over 10 min to a solution of 1.1 g (10.1 mmol) ofcyanogen bromide in 50 mL ether at 0° C. The solution was stirred for 2h, poured into aqueous sodium bicarbonate, dried over magnesium sulfate,and concentrated to give an oil. The crude product was purified bysilica gel chromatography eluting with ethyl acetate in hexanes(30%-50%). Concentration gave 2.7 g (80%) of N²-(tert-butoxycarbonyl)-N⁶ -(cyano)-L-lysine tert-butyl ester as acolorless, viscous oil. TLC (silica gel, ethylacetate:hexanes/1:1)Rf=0.5. IR (neat film) 2222 cm⁻¹ (CN). Mass Spectrum(CI 328 (MH⁺, 44%).

b. N² -(tert-butoxycarbonyl)-N² -(iminomethoxymethyl)-L-lysinetert-butyl ester hydrochloride

From 0.86 g (2.63 mmol) N² -(tert-butoxycarbonyl)-N⁶ -(cyano)-L-lysinetert-butyl ester was prepared 0.95 g (91%) N² -(tert-butoxycarbonyl)-N⁶-(iminomethoxymethyl)-L-lysine tert-butyl ester hydrochloride as afoamy-solid by the method described for the preparation of N²-(tert-butoxycarbonyl)-N⁵ -(iminomethoxymethyl)-L-ornithine tert-butylester hydrochloride. TLC (methanol: dichloromethane/1:9) Rf=0.36. Massspectrum (CI) 360 (MH⁺, 60%).

From 1.6 g (4.89 mmol) N² -(tert-butoxycarbonyl)-N⁶ -(cyano)-L-lysinetert-butyl ester was prepared 1.5 g (75%) of foamy solid N²-(tert-butoxycarbonyl)-N⁶ -(ethoxyiminomethyl)-L-lysine tert-butyl esterhydrochloride by the method described for N² -(tert-butoxycarbonyl)-N⁵-(iminomethoxymethyl)-L-ornithine tert-butyl ester hydrochloride. TLC(methanol:dichloromethane/1:9) Rf=0.36. Mass spectrum (CI) 360 (MH⁺,60%).

c.(i) N⁶ -(iminomethoxymethyl)-L-lysine dihydrochloride

From 0.70 g (1.77 mmol) N² -(tert-butoxycarbonyl)-N⁶-(iminomethoxymethyl)-L-lysine tert-butyl ester hydrochloride wasprepared 0.38 g (78%) N⁶ -(iminomethoxymethyl)-L-lysine dihydrochlorideby the method described above for the preparation of N⁵-(iminomethoxymethyl)-L-ornithine dihydrochloride TLC (silica gel,ammonium hydroxide:methanol/1:25) Rf=0.24.

c.(ii) N⁶ -(ethoxyiminomethyl)-L-lysine dihydrochloride

From 1.3 g (3.17 mmol) N² -(tert-butoxycarbonyl)-N⁶-(ethoxyiminomethyl)-L-lysine tert-butyl ester hydrochloride wasprepared 0.82 g (89%) N⁶ -(ethoxyiminomethyl)-L-lysine dihydrochlorideby the method described above for the preparation of N⁵-(iminomethoxymethyl)-L-ornithine dihydrochloride. TLC (4% ammoniumhydroxide: methanol) Rf=0.24. Mass spectrum (CI) 218 (MH⁺, 92%).

EXAMPLE 12 Preparation of 1-(3-(Aminomethyl)benzyl)-O-ethylisourea

a. Tert-butyl N-(3-(aminomethyl)benzyl)carbamate

10 g (73.42 mmol) of m-xylenediamine was added to 5.1 ml (36.71 mmol) oftriethylamine (Kodak) and 200 ml of anhydrous methanol. To this solutionat 0° C. was added a solution of 8.0 g (36.71 mmol) ofdi-t-butyldicarbonate in 60 ml of tetrahydrofuran dropwise over 60minutes. The solution was stirred and additional two hours at 0° C.,filtered, and concentrated to dryness. The crude material was purifiedby silica gel chromatography eluting with methanol/methylenechloride/ammonium hydroxide (5/95/0.5 to 15/85/0.5) to yield 5.28 g(30%) of a thick, viscous yellow oil.

b. 1-(3-(Aminomethyl)benzyl)-O-ethylisourea

1.2 g (5.08 mmol) of tert-butyl N-(3-(aminomethyl)benzyl)carbamate in 20ml ether was cooled to 0° C. and 538 mg (5.08 mmol) of cyanogen bromidewas added. The mixture was stirred for two hours, poured into saturatedsodium bicarbonate solution, and extracted with ether (2×100 ml) andethyl acetate (100 ml). The organic solutions were dried (sodiumsulphate), concentrated, and the resulting crude product was purified bysilica gel chromatography. Elution with methylene chloride followed by5% to 10% methanol in methylene chloride and concentration of theproduct fractions gave cyanamide intermediate as a white solid (91.08 g,82% yield). To a solution of 1.0 g (3.83 mmol) of the cyanamideintermediate in 10 ml of ethanol at 0° C, was added 3.83 ml (3.83 mmol)of 1.0M hydrochloric acid solution in anhydrous ether. The solution wasstirred for 16 hours, concentrated, and the resulting crude oil waspurified by silica gel chromatography eluting with methylene chloridefollowed by 5% to 20% methanol in methylene chloride to yield 1.22 g(92%) of ethyl acetimidate intermediate as a white coloured foam. To 1.0g (2.9 mmol) of this foam in 5 ml dioxane chilled to 10° C. was added 10ml (40 mmol) of 4N hydrochloric acid in dioxane solution. After stirringfor 6 hours, most of the solvent was removed under reduced pressure andthe residue remaining was treated with 20 ml of ether with rapidstirring. The resulting white solids were collected by filtration toyield 0.73 g (89%) of 1-(3-(Aminomethyl)benzyl)-O-ethylisourea. Massspectrum (CI) 208.0 (MH⁺, 68%).

EXAMPLE 13 Preparation of 1-(3-(Aminomethyl)benzyl)-S-methylisothiourea

a. Tert-butyl N-(3-((thioureidomethyl)benzyl)carbamate

A solution of 0.96 g (4.06 mmol) of tert-butyl N-(3-(aminomethyl)benzyl)carbamate in 20 ml chloroform was added to a 0° C. stirred mixture of0.975 g (9.75 mmol) calcium carbonate, 0.37 ml (4,87 mmol) thiophosgene,10 ml water, and 10 ml chloroform. After three hours the mixture wasfiltered and the aqueous phase was washed with chloroform. The organicswere dried (sodium sulphate), concentrated to an oil, and dissolved into50 ml of anhydrous methanol cooled to 0° C. Ammonia was bubbled for 5minutes and the solution was stirred for two hours. After concentrationto an oil, the crude product was dissolved into 50 ml ethyl acetate,washed with 50 ml water, dried (sodium sulphate), concentrated, andpurified by silica gel chromatography eluting with 50% to 80% ethylacetate in hexanes to provide 0.96 g (80%) of Tert-butylN-(3-((thioureido)methyl)benzyl)carbamate as a white foam.

b. 1-(3-(Aminomethyl)benzyl)-S-methylisothiourea

A solution of 0.34 g (1.15 mmol) tert-butylN-(3-((thioureido)methyl)benzyl) carbamate in 25 ml acetonitrile wastreated with 0.72 ml (11.51 mmol) iodomethane. The solution was stirredfor 22 hours and concentrated to yield 0.49 g (98%) of isothiourea as afoamy solid. This isothiourea intermediate (0.49 g) in 30 ml dioxane wastreated with 1.4 ml (5.6 mmol) of 4N hydrochloric acid in dioxanesolution. The reaction was stirred for five hours at 20° C. andconcentrated. The residue was freeze-dried from water (25 ml) and thenpurified by preparative reverse phase HPLC eluting withmethanol/water/trifluoroacetic acid (5/95/0.1) to yield 260 mg of clearcolourless 1-(3 -(Aminomethyl)benzyl)-S-methylisothiourea (46% yield,trifluoroacetic acid salt). Mass Spectrum (CI) 210.0 (MH⁺, 71.4%)

The following compound was made by an analogous method:

13A 1-(3-(Aminomethyl)benzyl)-S-ethylisothiourea

Mass Spectrum (CI) 224.0 (MH⁺, 74.6%)

EXAMPLE 14 Preparation of 1-(4-(Aminomethyl)benzyl)-S-metbylisothiourea

a. Tert-butyl N-(4-(aminomethyl)benzyl)carbamate

To a 0° C. stirred solution of 5.0 g (36.71 mmol) p-xylenediamine in 50ml tetrahydrofuran and 10 ml triethylamine was added 8.01 g (36.71 mmol)di-t-butyldicarbonate. The solution was stirred for six hours,concentrated, and extracted from water with ethyl acetate. The organicswere dried (sodium sulphate) and purified by silica gel chromatographyeluting with methanol in methylene chloride (0-60%). Concentration ofthe product fractions gave 0.96 g (11% yield) of tert-butylN-(4-(aminomethyl)benzyl)carbamate as a yellow solid.

b. 1-(4-(Aminomethyl)benzyl-S-methylisothiourea

From 2.31 g (9.77 mmol) of tert-butyl N-(4(aminomethyl)benzyl)carbamatewas prepared 0.43 g of 1-(4-(Aminomethyl)benzyl)-S-methylisothiourea bythe method described in example 13. Mass Spectrum (CI) 209.9 (MH⁺, 41%).

The following compound was prepared by an analagous method:

14A 1-(4-(Aminomethyl)benzyl)-S-ethylisothiourea

Mass Spectrum (CI) 224.0 (MH⁺, 60%)

EXAMPLE 15 Biological Activity

The activity of representative compounds of the present invention wasdetermined in accordance with the assay herein described.

Purification of NOS from human placenta

Amion and chorion were removed from fresh placenta, which was thenrinsed with 0.9% NaCl. The tissue was homogenized in a Waring blender in3 volumes of HEDS buffer (20 mM Hepes pH 7.8, 0.1 mM EDTA, 5 mM DTT, 0.2M sucrose) plus 0.1 mM PMSF. The homogenate was filtered throughcheesecloth and then centrifuged at 1000 g for 20 min. The supernatantwas recentrifuged at 27500 g for 30 min. Solid ammonium sulfate wasadded to the supernatant to give 32% saturation. Precipitated proteinwas pelleted at 25,000 g and then redissolved in a minimal volume ofHEDS buffer plus 0.1 mM PMSF, 10 μg/ml leupeptin and soybean trypsininhibitor, and 1 μg/ml pepstatin. The redissolved pellet was centrifugedat 15000 g for 10 min. To the supernatant was added 1/20 volume of 2',5'ADP agarose resin (Sigma), and the slurry was mixed slowly overnight. Inmorning, slurry was packed into a column. The resin was sequentiallywashed with HEDS, 0.5 M NaCl in HEDS, HEDS, and then NOS was eluted with10 mM NADPH in HEDS. The enzyme could be concentrated by ultrafiltrationand quick frozen and stored at -70° C. without loss in activity for atleast 6 months.

Assay for human placental NOS

NOS was assayed for the formation of citrulline following the procedureof Schmidt et al (PNAS88 365-369, 1991) with these modifications: 20 mMHepes, pH 7.4, 10 μg/ml calmodulin, 2.5 mM CaCl₂ 2.5 mM DTT, 125 μMNADPH 10 μM H4 Biopterin, 0.5 mg/ml BSA, and 1 μM L-[14C] arginine (NewEngland Nuclear). Linearity of NOS-catalyzed rate was confirmed prior tokinetic studies that used single time point determination of rate.

Purification of NOS cytokine-induced human colorectal adenocarcinomaDLD-1 cells.

DLD-1 (ATCC No. CCL 221) were groan at 37° C. 5% CO₂ in RPMI 1640 mediumsupplemented with L-glutamin, penicillin, streptomvcin, and 10%heat-inactivated fetal bovine serum. Cells were grown to confluency andthen the following cocktail of cytokines were added: 100 units/mlinterferon-gamma, 200 units/ml interleukin-6, 10 ng/ml tumor necrosisfactor, and 0.5 ng/ml interleukin-1β. At 10-24 hr post-induction, cellswere harvested by scraping and washed with phosphate-buffered saline.Pelleted cells were stored at -70° C. Purification of the induced NOSwas performed at 4° C. Crude extract was prepared by three cycles offreeze/thawing cells in TDGB (20 mM tris pH 7.5, 10% glycerol, 1 mM DTT,2 μM tetrahydrobiopterin). Extract was applied directly onto a column of2',5' ADP sepharse (Pharmacia). Resin was sequentially washed with TDGB,0.5 M NaCl in TDGB, TDGB. NOS was eluted with 2 mM NADPH in TDGB. BSAwas immediately added to give a final concentration of 1 mg/ml. NOScould be quick frozen and stored at -70° C. without loss in activity forat least 2 months.

Assay for inducible human NOS

The formation of citrulline was assayed as described above except that10 μM FAD was included and calmodulin and CaCl2 were excluded from theassay mix.

Purification of NOS from human brain

Human brain NOS was prepared using variations of the procedures ofSchmidt et al. (PNAS 88 365-369, 1991), Mayer et al. (Fed, Eur. Biochem.Soc. 288 187-191, 1991), and Bredt and Snyder, (PNAS 87 682-685, 1990).Briefly, frozen human brain (1050 gm) was homogenized in cold buffer A(50 mM HEPES, pH 7.5 (pH at RT) and 0.5 mM EDTA, 10 mM DTT, 3.6 L totalvolume) with a polytron. The mixture was centrifuged at 13,000 g for 1hour and the supernatant was removed (about 2050 ml). To thesupernatant, solid ammonium sulfate (365 gm, about 30% of saturation)was added and stirred slowly for a total of 30 minutes. The precipitatewas pelleted at 13,000 g for 30 minutes and the pellet was resuspendedin ˜400 mls of buffer A with 4 μM tetrthydrobiopterin, 1 μM FAD (Sigma),1 μM FMN (Sigma). The solution was centrifuged at 41,000 g for 60minutes. The supernatant was removed, frozen by pouring into liquidnitrogen, and stored overnight at -70° C. The mixture was thawed andpassed through a 2',5' ADP-agarose column (0.4 g swelled in buffer A) at4 ml/min. The column was washed with 100 ml buffer A 200 ml buffer Awith 500 mM NaCl, 100 ml Buffer A, then 30 ml buffer A with 5 mM NADPH.To the enzyme eluted from the column was added glycerol to 15%. CaCl₂ to1 mM. tetrahydrobiopterin to 10 μM, tween to 0.1% and FAD, FMN to 1 μMeach. The enzyme was then passed through a 1 ml calmodulin-agarosecolumn which had been equilibrated in Buffer A, 15% glycerol and 1 mMCaCl₂. The column was washed with 15 ml Buffer A, 15% glycerol and 1 mMCaCl₂, 15 ml of Buffer A, 15% glycerol and 5 mM EDTA, and then enzymeactivity was eluted with 3 ml of Buffer A, 15% glycerol and 5 mM EDTA, 1M NaCl. To the enzyme was added tetrahydrobiopterin to 10 μM, FAD andFMN to 1 μM, and tween to 0.1%. This solution was concentrated bycentriprep-30 to a volume of approximately 500 μl. Human NOS wasprepared completely analogously except the calinodulin-agarose columnwas not used. Enzyme activity was determined as described by Schmidt etal. 1991, except that 10 μM tetrahydrobiopterin was included in theassay. The results are as given in Table 1.

                  TABLE 1                                                         ______________________________________                                               Human         Human      Human                                                Inducible     Placental  Brain                                         Example                                                                              Ki/μM      Ki/μM   Ki/μM                                      ______________________________________                                        1      3.1           4.0        0.19 ± 0.01                                1A     3.2           3.1        0.56 ± 0.02                                1B     6.6           2.8        0.21 ± 0.01                                1C     >25           12         1.6                                           1D     0             14% @25 μm                                                                            30% @25 μm                                 1E     44            14         11                                            1F     4.7           2.0        0.25 ± 0.02                                1G     29            9.0         1.4 ± 0.01                                1H     28            14          1.5 ± 0.07                                1I     2.5           2.7        0.34                                          1J     4.9           2.7        0.29 ± 0.04                                1K     48% @25 μM 48% @25 μM                                                                            4.8                                           2      36% @25 μM 9.4        0.32 ± 0.02                                2A     0             0          11% @25 μM                                 2B     2.4           1.8        0.45                                          2C     10            6.5        1.13 ± 0.02                                2D     25            7.7        0.33                                          2E     3.2           28          1.1 ± 0.01                                2F     22            1.8         1.4 ± 0.01                                2G     2.9           1.8        0.17                                          2H     1.4           1.6        0.17 ± 0.02                                21     1.9           1.0        0.18 ± 0.04                                2J     47% @25 μM 6.9        1.0                                           2K     17            8.2        4.2                                           2L     20%            6%        40%                                           2M     23            6.9        1.0 ± 0.2                                  2N     22            16         0.8 ± 0.2                                  3       4%           14%        24%                                           3A     12%           35%        1.9 ± 0.1                                  5      3.3           5.5                                                      5A     11            21                                                       6      2.3           17         0.5                                           7      45            22         3.2                                           8      0.034a        0.07b      0.001c                                        9      0.028b        0.030a     0.0005c                                       9A     1.7           4.1        0.09                                          9B     0.69          3.3        3.0                                           9C     0.15          2.1        0.9                                           9D     22.6          23.2       28                                            9E     5.3           14         5.5                                           9F                   79         61                                            9G     3.6           3.7        0.2                                           9H     5.3           1.2        0.4                                           9I     15            11         11                                            9J     7.0           1.3        0.56                                          9K     40            30         61                                            9L     19            23         108                                           9M     13                       19.5                                          9N                   99         61                                            10c (i)                                                                              0.22b         0.12b      0.10b                                         10c (ii)                                                                             0.10b         0.006a     0.002c                                        12     1.7           4.1        0.09                                          13     0.69          3.3        3.0                                           13A    0.15          2.1        0.9                                           14     22.6          23.2       28                                            14A    5.3           14         5.5                                           ______________________________________                                         .sup.a The progress curve was an exponential decay followed by a linear       steady state rate. Inhibition constant was calculated by dividing the         steady state inhibited rate by the control uninhibited rate; percent          inhibition was then used to calculate the inhibition constant assuming        competitive inhibition with respect to arginine.                              .sup.b Value obtained from measuring percent inhibition at three or more      concentrations of inhibitor at a single time point and assuming               competitive inhibition with respect to arginine.                              .sup.c The progress curve was an exponential decay of the rate. Value is      K.sub.d determined by measuring association and dissociation rate             constants for the slow onset of inhibition, as previously described           (Furfine, E. S., Harmon, M. F., Paith, J. E., and Garvey, E. P. (1993)        Biochemistry 32, 8512-8517).                                             

We claim:
 1. A method of treatment of a condition requiring selectiveinhibition of the neuronal NO synthase enzyme comprising administeringto a mammal in need thereof a therapeutically effective amount orS-ethyl-N-[(4-trifluoromethyl)phenyl]isothiourea or a salt, ester oramide thereof.
 2. A method as claimed in claim 1, wherein the conditionis selected from the group consisting of cerebral ischemia, CNS trauma,epilepsy, AIDS dementia, chronic neurodegenerative disease, chronicpain, priapism, obesity, hyperphagia and combinations thereof.
 3. Amethod as claimed in claim 2 wherein the condition is cerebral ischemia.